The second type of disorder is due to random values of the interlayer coupling \(\gamma _1\)  which preserve chiral symmetry. For a given realization of disorder, elements of the non-interacting Hamiltonian (REF ) describing interlayer coupling take random values, i.e. \(H_{B_1A_2} = H_{A_2B_1} = \gamma _1 + \delta _1\) , \(H_{B_2A_3} = H_{A_3B_2} = \gamma _1 + \delta _2\) , etc., \(n = 1,2,3,\ldots , N-1\) , where each \(\delta _n\)  takes a random value uniformly distributed in the range \([-\delta , \delta ]\)  for disorder strength \(\delta \) . Figure REF  shows the dependence of the mean values of \(E_g\)  and \(\Delta \)  for \(N=12\)  layers as a function of disorder strength \(\delta \)  for the odd parity antiferromagnetic state, each data point (circles) is an average over twenty different realizations of disorder. We find that the mean value of \(\Delta \)  is not affected by disorder (within the error bars), and that disorder slightly reduces the mean value of \(E_g\)  for the weak disorder values we consider. This is in line with studies of the SSH model [1]}, [2]}, [3]}, [4]}, [5]} where one expects chiral-preserving disorder to have a negligible effect on the zero-energy edge states, although the exchange interaction has already broken chiral symmetry in the interacting mean-field state considered here.
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